Jump to content

Wiring Right? P90 seems darker than I remember.


tparker
 Share

Recommended Posts

Think I got the wiring done correctly, but would appreciate review. I'm happy with features and layout, but wondering about some things. Here's a diagram of what I did. Sorry I can't figure out how to center things in Inkscape.

*I had no output at first. Seems that I got a bad pot. Bypassed it and it works fine. Wiper is not lined up with the beginning of the sweep. Ordered new pot.

*The P90 doesn't have much volume compared to humbucker. This was expected, but more than I thought.

*The P90 is a lot muddier than I remember. I've had this pickup in other guitars and thought it was louder and brighter. But maybe my taste has changed?

*Thinking of ways to brighten up the p90. Maybe add a resister to the pot to make it 750? No one makes a 750 or 1 meg pot switch combo it seems. Or maybe the p90 has a short and needs to be rewound?

Thoughts?

royal wiring2.png

Link to comment
Share on other sites

Interesting circuit. I assume you're using the two blend pots to essentially dial in two pickup mix 'settings' and switch between the two, rather than explicitly switch between neck and bridge pickups. For added player confusion you could conceivably dial each of the two blend pots to 100% neck and bridge and effectively reverse the switching of bridge and neck pickups if you wanted ;) :D

What are the values/tapers of your pots? Are they the dedicated blend pots from Stewmac or are they just generic dual gang pots?

It could be that the P90 might be getting loaded down too much. At any one time in your circuit you effectively have 3 volume pots and 2 tone pots connected to each  pickup, which in most guitars would probably be considered a fairly heavy load for a pickup to drive. That could potentially lead to the pickups having a dull output.

 

1 hour ago, tparker said:

Maybe add a resister to the pot to make it 750?

Won't work unfortunately. You can't add a resistor to a pot to make it appear 'bigger' to the pickup.

 

2 hours ago, tparker said:

No one makes a 750 or 1 meg pot switch combo it seems.

https://guitarelectronics.com/bourns-1meg-audio-taper-guitar-pot-w-push-pull-switch/

 

1 hour ago, tparker said:

Just noticed I labeled the caps wrong. .047 is on humbucker tone control.

Welllll, you don't explicitly have a humbucker tone control as such. Your tone circuit is connected after the blending, so you really have independent tone controls of each of the two pickup blends, rather than each individual pickup.

Link to comment
Share on other sites

Actually, on second look I'm a little curious if it works properly at all.

Consider if you wind up blend pot A to 100% P90 and blend pot B down to 0% P90. Blend pot B will short the P90 signal to ground and you'll end up with no signal at all, even though you're expecting blend pot A to provide 100% P90 signal. If you reverse the blend pot settings (A = 0%, B = 100%) you get the same problem. Same goes with the humbucker pickup signal too. And it's also irrespective of which blend signal you select using the toggle switch.

The best you can expect from the circuit is if both blend pots are set to 50% and the volume pot at max. Possibly another reason why the P90 sounds so dull.

Link to comment
Share on other sites

Yup, you got it Curtis. Did some testing. When I set the blends to 50% it gets a volume and tone boost. What I'm now perplexed about is why it doesn't boost again when you set both to p90 or humbucker? Wouldn't it wall off the signal from ground. What am I missing?

Ugh, looks like I'm looking at a triple pole switch to keep the channels totally isolated. Was hoping to avoid that wiring mess.

I think I also saw a post about not grounding the blend pot..... That would be really cool to not have to put in a triple pole switch.

Link to comment
Share on other sites

34 minutes ago, tparker said:

What I'm now perplexed about is why it doesn't boost again when you set both to p90 or humbucker? Wouldn't it wall off the signal from ground. What am I missing?

If you set both blend pots to 100% P90 (or both to 100% humbucker), you've still got the P90 signal connected to both blend pots in parallel. Two equal value resistors in parallel result in a combined resistance of half the value of one of the resistors. So if your blend pot is 250K, the P90 'sees' the two blend pots in parallel and is loaded by both, and the effective resultant blend pot is actually only 125K. The output cannot reach its full potential and you end up slugging the P90 signal harder than you would if you just had a single volume pot of 250K.

It's made even worse by the addition of the master volume pot, which further slugs the output. And the tone pot. It's probable that both the P90 and Humbucker are struggling to push the signal out; it's just that the P90 struggles the most and is the pickup that becomes the most obvious to your ears in doing so.

 

41 minutes ago, tparker said:

Ugh, looks like I'm looking at a triple pole switch to keep the channels totally isolated. Was hoping to avoid that wiring mess.

I think the easy fix is to utilise the unused half of the selector switch at the bottom-left of your diagram to disconnect the ground from the 'de-selected' blend control (my additions/mods in purple):

image.png

You might still get some minor cross-coupling wierdness between the two pickups at either extreme of the blend pot rotation, but I think you'll get an improvement in output, and it should certainly alleviate the issue with the blend pots cutting off the signal when they're both set to opposite extremes.

As you say, anything more fancy than this will likely require a three pole switch and a significant amount of spaghetti inside your guitar ;)

Link to comment
Share on other sites

2 hours ago, tparker said:

Still not following the math on the pots, but will print out the drawing and try to wrap the brain around it.

If you're not familiar with converting a wiring diagram to a schematic it's a bit hard to visualise. Think of it a bit like having a car (the pickup) tow a trailer (the output signal). As you start throwing more weight into the trailer (volume pots, tone controls, blend pots) the car starts struggling more to move the load behind it.

PS - moved to the electronics subforum.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...